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We used finite element analysis to study the mechanical displacements at three planes of the second through fourth hammertoes during the push-off phase of gait using a new neutral or 10° angled memory alloy intramedullary implant (FDA K070598) used for proximal interphalangeal joint arthrodesis.
After geometric reconstruction of the foot skeleton from computed tomographic images of a 36-year-old man, an intramedullary implant was positioned in the virtual model at the neutral and 10° angled positions at the proximal interphalangeal joints of the second through fourth hammertoes during the push-off phase of gait. The obtained displacement results in three planes were compared with those derived from the nonsurgical foot model using finite element analysis.
These results support the successful use of either a neutral or angled implant for proximal interphalangeal joint arthrodesis, with the neutral implant yielding slightly better results.
The neutral implant reduced vertical displacement to a greater extent than did the angled implant. We also highlight the potential risk of iatrogenic curly toe when performing a proximal interphalangeal joint arthrodesis using an angled implant specifically at the fourth toe.